U.S. President Joe Biden called on Russia on Friday to release detained Wall Street Journal reporter Evan Gershkovich, who was charged with spying by Moscow.
Russia's FSB security service said on Thursday it had detained Gershkovich, the most serious public move against a foreign journalist since Russia invaded Ukraine.
"Let him go," Biden said as he left the White House for a trip to storm-ravaged Mississippi.
Asked if he was going to expel Russian diplomats after the detention of Gershkovich, Biden said, "That's not the plan right now."
The White House press secretary, Karine Jean-Pierre, called the espionage charges "ridiculous" on Thursday and said there was no evidence to support the claim.
The Journal said the detention of Gershkovich was based on false allegations.
The FSB accused Gershkovich of gathering information classified as a state secret about a military factory.
It did not name the factory or say where it was, but said it had detained the 31-year-old journalist in the Urals city of Yekaterinburg as he was trying to procure secret information. It did not provide documentary or video evidence of his guilt.
(Reporting by Doina Chiacu; Editing by William Maclean)